KR20230061572A - Metal sheet, method for manufacturing metal sheet, and method for manufacturing vapor deposition mask using metal sheet - Google Patents

Abstract

An object of the present invention is to provide a metal plate capable of fabricating a deposition mask in which fluctuations in positions of through holes are suppressed. A percentage per million of the difference in the distance before and after the heat treatment with respect to the distance between the two measurement points in the sample before the heat treatment is defined as the thermal recovery rate. In this case, the average value of the thermal recovery rate in each sample is -10 ppm or more and +10 ppm or less, and the variation in the thermal recovery rate in each sample is 20 ppm or less.

Description

A metal plate, a method for manufacturing a metal plate, and a method for manufacturing a deposition mask using a metal plate

The present invention relates to a metal plate used for manufacturing a deposition mask by forming a plurality of through holes. Moreover, this invention relates to the manufacturing method of a metal plate. Further, the present invention relates to a method for manufacturing a mask having a plurality of through holes using a metal plate.

In recent years, display devices used in portable devices such as smartphones and tablet PCs are required to be highly precise, for example, to have a pixel density of 300 ppi or higher. In addition, even in a portable device, the demand for a device compatible with full high-vision is increasing, and in this case, the pixel density of the display device is required to be 450 ppi or more, for example.

Due to good responsiveness and low power consumption, organic EL display devices are attracting attention. As a method of forming pixels of an organic EL display device, a method of forming pixels in a desired pattern using a deposition mask including through holes arranged in a desired pattern is known. Specifically, first, a deposition mask is brought into close contact with a substrate for an organic EL display device, and then, the adhered deposition mask and substrate are put together into a deposition apparatus to deposit an organic material or the like. A deposition mask can generally be manufactured by forming a through hole in a metal plate by etching using a photolithography technique (for example, Patent Document 1). For example, first, a resist film is formed on a metal plate, then the resist film is exposed in a state where an exposure mask is brought into close contact with the resist film to form a resist pattern, and then the area of the metal plate not covered by the resist pattern By etching, a through hole is formed.

(Patent Document 1) Japanese Unexamined Patent Publication No. 2004-39319

When a deposition material is deposited on a substrate using a deposition mask, the deposition material is attached to the deposition mask as well as the substrate. For example, some evaporation materials are directed toward the substrate along a direction greatly inclined with respect to the normal direction of the deposition mask, but such evaporation materials reach the wall surface of the through hole of the deposition mask before reaching the substrate and adhere thereto. do. In this case, it is difficult for the evaporation material to adhere to a region of the substrate located near the wall surface of the through hole of the deposition mask. It is conceivable that a part may occur. That is, it is considered that vapor deposition in the vicinity of the wall surface of the through hole of the deposition mask becomes unstable. Therefore, when a deposition mask is used to form the pixels of the organic EL display device, the dimensional accuracy and positional accuracy of the pixels are lowered, and as a result, the luminous efficiency of the organic EL display device is lowered.

In order to solve such a subject, it is considered to reduce the thickness of the metal plate used to manufacture the deposition mask. This is because, by reducing the thickness of the metal plate, the height of the wall surface of the through hole of the deposition mask can be reduced, thereby reducing the ratio of deposition materials adhering to the wall surface of the through hole. However, in order to obtain a metal sheet having a small thickness, it is necessary to increase the rolling ratio when manufacturing a metal sheet by rolling a base material. Here, the rolling ratio is a value calculated by (thickness of the base material-thickness of the metal plate)/(thickness of the base material). When a metal is rolled, deformation occurs inside the metal. Even when heat treatment such as annealing is performed after rolling, it is not easy to completely remove such strain in a short time. Therefore, in the metal plate used to fabricate the deposition mask, there is usually a strain remaining inside the metal plate, that is, a residual strain.

By the way, a process of manufacturing a deposition mask using a metal plate or a deposition process using a deposition mask includes a process of applying heat to the metal plate constituting the deposition mask. At this time, there are cases where residual stress in the metal sheet is removed due to heat or the arrangement of crystals is changed. When the residual stress is removed or the arrangement of crystals is changed, the size of the metal sheet may be shortened. For example, when the residual stress is removed, the shape of the material held by the residual stress is changed so that deformation is eliminated as much as possible, so the dimension of the metal plate may be shortened. In addition, when the arrangement of the crystals is changed, the crystal density is changed so that the density becomes higher, so the size of the metal plate may be shortened.

The fact that the size of the metal plate constituting the deposition mask can be changed by heat means that the position of the through hole formed in the deposition mask can be changed by heat. In addition, there may be cases where the degree of residual strain inside the metal plate differs in the width direction of the metal plate. In this case, the degree to which the positions of the through holes are changed by heat varies depending on the position in the width direction occupied by the metal plate constituting the deposition mask in the basic long metal plate. This means that not only the position of the through hole formed in the deposition mask is changed by heat, but also the degree of change is different for each individual deposition mask. Therefore, in order to precisely set the position of the through hole of each deposition mask, it is important to use a long metal plate that is the base and has a small degree of residual strain and a small variation thereof. Such a subject was not recognized in Patent Document 1 described above.

The present invention has been made in view of such a subject, and an object of the present invention is to provide a metal plate used for manufacturing a deposition mask having through holes formed with high positional accuracy. Moreover, an object of this invention is to provide the manufacturing method of a metal plate, and the manufacturing method of a mask.

The present invention is a method for manufacturing a metal plate used for manufacturing a deposition mask by forming a plurality of through holes,

The through hole of the deposition mask is formed by etching the metal plate;

The manufacturing method of the metal plate,

A rolling step of obtaining the metal sheet by rolling a base material;

Annealing process of annealing the metal plate obtained by the rolling process

to provide,

The distance between two measurement points on each sample, measured before and after heat treatment on a plurality of samples taken out from the metal plate, is L1 and L2, respectively, and the heat recovery rate F of each sample is expressed by the following formula

F={(L1-L2)/L1}×10 ⁶ (ppm)

When defined by, the following conditions (1) and (2) are satisfied,

(1) that the average value of the thermal recovery rate in each of the above samples is -10 ppm or more and +10 ppm or less; and,

(2) Variation in thermal recovery rate in each of the above samples is 20 ppm or less;

The sample is obtained by cutting a plurality of at least one sample metal plate obtained by cutting the metal plate along the width direction of the metal plate along the longitudinal direction of the metal plate,

The two measuring points on the sample are arranged along the longitudinal direction of the metal plate,

The heat treatment includes a first step of raising the temperature of each sample from 25 ° C to 300 ° C for 30 minutes, a second step of maintaining the temperature of each sample at 300 ° C for 5 minutes, and A third step of lowering the temperature from 300 ° C. to 25 ° C. for 60 minutes,

The variation of the heat recovery rate is a value calculated by multiplying the standard deviation of the heat recovery rate of each sample by 3, according to the manufacturing method of the metal plate.

In the method for manufacturing a metal sheet according to the present invention, the annealing step may be performed while pulling the rolled base material in the longitudinal direction. Alternatively, the annealing step may be performed on the metal sheet wound around a core.

In the method for manufacturing a metal sheet according to the present invention, the base material may be composed of an invar material.

The present invention is a metal plate used to manufacture a deposition mask by forming a plurality of through holes,

The through hole of the mask is formed by etching the metal plate,

The distance between two measurement points on each sample, measured before and after heat treatment on a plurality of samples taken out from the metal plate, is L1 and L2, respectively, and the heat recovery rate F of each sample is expressed by the following formula

F={(L1-L2)/L1}×10 ⁶

When defined by, the following conditions (1) and (2) are satisfied,

(1) that the average value of the thermal recovery rate in each of the above samples is -10 ppm or more and +10 ppm or less; and,

(2) Variation in thermal recovery rate in each of the above samples is 20 ppm or less;

The sample is obtained by cutting a plurality of at least one sample metal plate obtained by cutting the metal plate along the width direction of the metal plate along the longitudinal direction of the metal plate,

The two measuring points on the sample are arranged along the longitudinal direction of the metal plate,

The heat treatment includes a first step of raising the temperature of each sample from 25 ° C to 300 ° C for 30 minutes, a second step of maintaining the temperature of each sample at 300 ° C for 5 minutes, and A third step of lowering the temperature from 300 ° C. to 25 ° C. for 60 minutes,

The variation of the heat recovery rate is a value calculated by multiplying the standard deviation of the heat recovery rate of each sample by 3, and is a metal plate.

The metal sheet according to the present invention may be composed of an invar material.

The present invention is a method for manufacturing a deposition mask having a plurality of through holes,

A process of preparing a metal plate;

a resist pattern forming step of forming a resist pattern on the metal plate;

an etching step of etching a region of the metal plate not covered by the resist pattern to form a concave portion in the metal plate to define the through hole;

The distance between two measurement points on each sample, measured before and after heat treatment on a plurality of samples taken out from the metal plate, is L1 and L2, respectively, and the heat recovery rate F of each sample is expressed by the following formula

F={(L1-L2)/L1}×10 ⁶

When defined by, the following conditions (1) and (2) are satisfied,

(1) that the average value of the thermal recovery rate in each of the above samples is -10 ppm or more and +10 ppm or less; and,

(2) Variation in thermal recovery rate in each of the above samples is 20 ppm or less;

The sample is obtained by cutting a plurality of at least one sample metal plate obtained by cutting the metal plate along the width direction of the metal plate along the longitudinal direction of the metal plate,

The two measuring points on the sample are arranged along the longitudinal direction of the metal plate,

The heat treatment includes a first step of raising the temperature of each sample from 25 ° C to 300 ° C for 30 minutes, a second step of maintaining the temperature of each sample at 300 ° C for 5 minutes, and A third step of lowering the temperature from 300 ° C. to 25 ° C. for 60 minutes,

The deviation of the thermal recovery rate is a value calculated by multiplying the standard deviation of the thermal recovery rate of each sample by 3, according to the method for manufacturing a deposition mask.

In the method for manufacturing a deposition mask according to the present invention, the resist pattern forming step comprises:

A step of forming a resist film on the metal plate, a step of bringing an exposure mask into vacuum contact with the resist film, a step of exposing the resist film in a predetermined pattern through the exposure mask, and forming an image on the exposed resist film. There is a developing step for doing so, and the developing step may include a resist heat treatment step for increasing the hardness of the resist film.

In the method for manufacturing a deposition mask according to the present invention, the metal plate may be made of an invar material.

According to the present invention, it is possible to obtain a deposition mask in which fluctuations in the positions of through holes are suppressed. Due to this, it is possible to increase the positional accuracy of the evaporation material deposited on the substrate.

1 is a diagram for explaining an embodiment of the present invention, and is a schematic plan view showing an example of a deposition mask device including a deposition mask.
FIG. 2 is a diagram for explaining a method of depositing using the deposition mask device shown in FIG. 1;
FIG. 3 is a partial plan view illustrating the deposition mask shown in FIG. 1 .
4 is a cross-sectional view along line IV-IV of FIG. 3 .
FIG. 5 is a cross-sectional view along line V-V of FIG. 3 .
FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 3 .
Fig. 7(a) is a diagram showing a step of rolling a base material to obtain a metal plate having a desired thickness, and Fig. 7(b) is a diagram showing a step of annealing the metal plate obtained by rolling.
Fig. 8 (a) is a plan view showing the elongated metal plate, Fig. 8 (b) is a plan view showing a sample metal plate cut out from the elongated metal plate, and Fig. 8 (c) shows a sample cut out from the sample metal plate. It is a plan view of
9A is a diagram showing heat treatment performed on a sample.
9B (a) and (b) are plan views showing samples before and after heat treatment, respectively.
FIG. 10 is a schematic diagram for explaining an example of a manufacturing method of the deposition mask shown in FIG. 1 as a whole.
11 is a diagram for explaining an example of a method for manufacturing a deposition mask, and is a cross-sectional view showing a step of forming a resist film on a metal plate.
12 is a diagram for explaining an example of a method for manufacturing a deposition mask, and is a cross-sectional view showing a step of bringing an exposure mask into close contact with a resist film.
13 is a diagram for explaining an example of a method for manufacturing a deposition mask, and is a diagram showing an elongated metal plate in a cross section along a normal direction.
14 is a diagram for explaining an example of a method for manufacturing a deposition mask, and is a diagram showing an elongated metal plate in a cross section along a normal direction.
15 is a diagram for explaining an example of a method for manufacturing a deposition mask, and is a diagram showing an elongated metal plate in a cross section along a normal direction.
16 is a diagram for explaining an example of a method for manufacturing a deposition mask, and is a diagram showing an elongated metal plate in a cross section along a normal direction.
17 is a diagram for explaining an example of a method for manufacturing a deposition mask, and is a diagram showing an elongated metal plate in a cross section along a normal direction.
18 is a diagram for explaining an example of a method for manufacturing a deposition mask, and is a diagram showing an elongated metal plate in a cross section along a normal direction.
19 is a diagram for explaining an example of a method for manufacturing a deposition mask, and is a diagram showing an elongated metal plate in a cross section along a normal direction.
20 is a diagram showing a modified example of a deposition mask device including a deposition mask.
Fig. 21 is a diagram showing measurement results of heat recovery rates in samples 1 to 10 cut out from first to 10 winding bodies.
Fig. 22 is a diagram showing evaluation results of the first-order effect in the deposition mask made of the elongated metal plate obtained from the first to tenth winding bodies.
23 is a diagram showing evaluation results of the secondary effect in the deposition mask made of the elongated metal plate obtained from the first to tenth winding bodies.

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of this invention is described with reference to drawings. In addition, in the drawings attached to this specification, for convenience of illustration and understanding, the scale and the size ratio of length and width are appropriately exaggerated by changing from the actual scale and size ratio of length and width.

1 to 19 are diagrams for explaining an embodiment according to the present invention. In the following embodiments and modifications thereof, a method for manufacturing a deposition mask used for patterning an organic material on a substrate in a desired pattern when manufacturing an organic EL display device will be described as an example. However, it is not limited to these applications, and the present invention can be applied to methods of manufacturing deposition masks used for various purposes.

In addition, in this specification, the terms "plate", "sheet", and "film" are not distinguished from each other based only on differences in names. For example, a "plate" is a concept that includes members that can be called sheets and films, and therefore, for example, a "metal plate" can be distinguished from a member called a "metal sheet" or a "metal film" only by a difference in name. It can't be.

Further, "plate surface (sheet surface, film surface)" refers to the plane of the target plate-like member (sheet-like member, film-like member) when the target plate-like (sheet-like, film-like) member is viewed as a whole and as a whole. Points to the side that coincides with the direction. In addition, the normal direction used for a plate-shaped (sheet-like, film-like) member refers to the normal direction with respect to the plate surface (sheet surface, film surface) of the member.

In addition, terms such as "parallel", "orthogonal", "equal", "equivalent", etc., lengths, angles, and Regarding the values of the physical characteristics, etc., analysis will be made including a range within which similar functions can be expected without being bound by strict meanings.

(deposition mask device)

First, an example of a deposition mask device including a deposition mask to be manufactured will be described with reference to FIGS. 1 to 6 . Here, FIG. 1 is a plan view showing an example of a deposition mask device including a deposition mask, and FIG. 2 is a diagram for explaining a method of using the deposition mask device shown in FIG. 1 . 3 is a plan view showing the deposition mask from the first surface side, and FIGS. 4 to 6 are sectional views at respective positions in FIG. 3 .

The deposition mask device 10 shown in FIGS. 1 and 2 includes a plurality of deposition masks 20 including substantially rectangular metal plates 21 and a frame 15 installed on the periphery of the plurality of deposition masks 20 . is provided. In each deposition mask 20, a plurality of through holes 25 formed by etching the metal plate 21 having first and second surfaces 21a and 21b that face each other from at least the first surface 21a are formed. has been As shown in FIG. 2, the deposition mask device 10 is supported in the deposition device 90 so that the deposition mask 20 faces the lower surface of a substrate, for example, a glass substrate 92 as a deposition target. , used for the deposition of deposition materials onto substrates.

Inside the deposition apparatus 90, the deposition mask 20 and the glass substrate 92 are brought into close contact with each other by magnetic force from a magnet (not shown). Inside the deposition apparatus 90, below the deposition mask apparatus 10, a crucible 94 for accommodating an evaporation material (an organic light emitting material as an example) 98, and a heater 96 for heating the crucible 94 ) is placed. The evaporation material 98 in the crucible 94 is vaporized or sublimated by heating from the heater 96 to adhere to the surface of the glass substrate 92 . As described above, a plurality of through holes 25 are formed in the deposition mask 20 , and the deposition material 98 is attached to the glass substrate 92 through the through holes 25 . As a result, the deposition material 98 is formed on the surface of the glass substrate 92 in a desired pattern corresponding to the position of the through hole 25 of the deposition mask 20 .

As described above, in this embodiment, the through holes 25 are arranged in a predetermined pattern in each effective region 22 . Further, when color display is desired, the deposition mask 20 (deposition mask device 10) and the glass substrate 92 are relatively moved little by little along the arrangement direction of the through holes 25 (one direction described above). Then, the organic light emitting material for red, the organic light emitting material for green, and the organic light emitting material for blue may be sequentially deposited.

Further, the frame 15 of the deposition mask device 10 is provided on the periphery of the rectangular deposition mask 20 . The frame 15 holds the deposition mask attached so that the deposition mask 20 does not bend. The deposition mask 20 and the frame 15 are fixed to each other by, for example, spot welding.

The vapor deposition process is performed inside the vapor deposition apparatus 90 in a high-temperature atmosphere. Therefore, during the deposition process, the deposition mask 20, the frame 15, and the substrate 92 held inside the deposition apparatus 90 are also heated. At this time, the deposition mask, the frame 15, and the substrate 92 exhibit dimensional change behavior based on their respective coefficients of thermal expansion. In this case, if the thermal expansion coefficients of the deposition mask 20 or frame 15 and the substrate 92 differ greatly, positional displacement due to the difference in dimensional change between them occurs, resulting in adhesion on the substrate 92. The dimensional accuracy and positional accuracy of the evaporation material to be used will decrease. In order to solve such a problem, it is preferable that the thermal expansion coefficient of the deposition mask 20 and the frame 15 be equal to the thermal expansion coefficient of the substrate 92 . For example, when a glass substrate 92 is used as the substrate 92, a predetermined amount of nickel, for example, 36% by mass of nickel is added to iron as the material of the deposition mask 20 and the frame 15. An invar material, which is an added iron alloy, can be used.

(deposition mask)

Next, the deposition mask 20 will be described in detail. As shown in FIG. 1 , in this embodiment, the deposition mask 20 includes the metal plate 21 and has a substantially rectangular outline in plan view, more precisely, a substantially rectangular outline in plan view. The metal plate 21 of the deposition mask 20 includes an effective area 22 in which through holes 25 are formed in a regular arrangement, and a peripheral area 23 surrounding the effective area 22 . The peripheral area 23 is an area for supporting the effective area 22 and is not an area through which evaporation material intended to be deposited on the substrate passes. For example, in the deposition mask 20 used for depositing the organic light emitting material for an organic EL display device, the effective area 22 is a substrate (glass substrate 92) on which the organic light emitting material is deposited to form pixels. ), that is, a region within the deposition mask 20 facing the region on the substrate that will form the display surface of the fabricated substrate for the organic EL display device. However, for various purposes, a through hole or a recess may be formed in the peripheral region 23 . In the example shown in Fig. 1, each effective area 22 has an outline of a substantially rectangular shape in plan view, and more accurately, a substantially rectangular outline in plan view.

In the illustrated example, the plurality of effective regions 22 of the deposition mask 20 are arranged in a line at predetermined intervals along one direction parallel to the longitudinal direction of the deposition mask 20 . In the illustrated example, one effective area 22 corresponds to one organic EL display device. That is, according to the deposition mask device 10 (deposition mask 20) shown in FIG. 1, multi-layered deposition is possible.

As shown in FIG. 3 , in the illustrated example, a plurality of through holes 25 formed in each effective area 22 are formed along two directions orthogonal to each other in the effective area 22, respectively. arranged in pitch. An example of the through hole 25 formed in the metal plate 21 will be described in more detail with reference mainly to FIGS. 3 to 6 .

As shown in FIGS. 4 to 6 , the plurality of through holes 25 extend along the normal direction of the deposition mask 20 and the first surface 20a that is one-sided along the normal direction of the deposition mask 20 . It extends between the second surfaces 20b on the other side, and penetrates the deposition mask 20. In the illustrated example, as described in detail later, the first concave portion 30 is etched in the metal plate 21 from the first surface 21a side of the metal plate 21 on one side in the normal direction of the deposition mask. , and a second concave portion 35 is formed in the metal plate 21 from the side of the second surface 21b, which is the other side in the normal direction of the metal plate 21, and the first concave portion 30 and A through hole 25 is formed by the second concave portion 35 .

3 to 6, at each position along the normal direction of the deposition mask 20 from the first surface 20a side of the deposition mask 20 toward the second surface 20b side. The cross-sectional area of each first concave portion 30 in the cross section along the plate surface of the deposition mask 20 gradually decreases. As shown in FIG. 3 , the wall surface 31 of the first concave portion 30 extends in a direction crossing the normal direction of the deposition mask 20 over its entire area, and the deposition mask 20 It is exposed toward one side along the normal direction of . Similarly, the cross-sectional area of each second concave portion 35 in the cross section along the plate surface of the deposition mask 20 at each position along the normal direction of the deposition mask 20 is the second surface of the deposition mask 20. It may be made smaller gradually from the (20b) side toward the first surface 20a side. The wall surface 36 of the second concave portion 35 extends in a direction crossing the normal direction of the deposition mask 20 over its entire area, and extends on the other side along the normal direction of the deposition mask 20. are exposed towards

4 to 6, the wall surface 31 of the first concave portion 30 and the wall surface 36 of the second concave portion 35 are connected via a circumferential connection portion 41. has been The connection portion 41 includes a wall surface 31 of the first concave portion 30 inclined with respect to the normal direction of the deposition mask and a wall surface 36 of the second concave portion 35 inclined with respect to the normal direction of the deposition mask. It is partitioned by the ridgeline of this confluence protrusion. Then, the connecting portion 41 defines a penetrating portion 42 in which the area of the through hole 25 is the smallest in plan view of the deposition mask 20 .

As shown in FIGS. 4 to 6, on the other surface along the normal direction of the deposition mask, that is, on the second surface 20b of the deposition mask 20, the two adjacent through holes 25 are, They are spaced apart from each other along the plane of the deposition mask. That is, as in the manufacturing method described later, the metal plate 21 is etched from the side of the second surface 21b of the metal plate 21 corresponding to the second surface 20b of the deposition mask 20 to form the second concave portion. In the case of manufacturing 35, the second surface 21b of the metal plate 21 remains between two adjacent second concave portions 35.

Meanwhile, as shown in FIGS. 4 to 6 , two first concave portions 30 adjacent to each other on one side along the normal direction of the deposition mask, that is, on the side of the first surface 20a of the deposition mask 20 . ) is connected. That is, as in the manufacturing method described later, the metal plate 21 is etched from the side of the first surface 21a of the metal plate 21 corresponding to the first surface 20a of the deposition mask 20 to form the first concave portion. In the case of forming 30, the first surface 21a of the metal plate 21 does not remain between the two adjacent first concave portions 30. That is, the first surface 21a of the metal plate 21 is etched over the entire area of the effective area 22 . According to the first surface 20a of the deposition mask 20 formed by the first concave portion 30, as shown in FIG. 2, the first surface 20a of the deposition mask 20 is a deposition material ( 98), the use efficiency of the evaporation material 98 can be effectively improved.

When the deposition mask device 10 is accommodated in the deposition device 90 as shown in FIG. 2, as shown by the dashed-two dotted line in FIG. 4, the first surface 20a of the deposition mask 20 is deposited. It is located on the side of the crucible 94 holding the material 98, and the second surface 20b of the deposition mask 20 faces the glass substrate 92. Thus, the evaporation material 98 passes through the first concave portion 30 whose cross-sectional area gradually decreases and adheres to the glass substrate 92 . As indicated by the arrows in FIG. 4 , the deposition material 98 not only moves along the direction normal to the glass substrate 92 from the crucible 94 toward the glass substrate 92, but also moves in the direction normal to the glass substrate 92. It may also move in a direction that is greatly inclined with respect to . At this time, if the thickness of the deposition mask 20 is large, most of the evaporation material 98 moving obliquely passes through the through hole 25 before reaching the glass substrate 92. It reaches and attaches to the wall surface 31 . In this case, in the region facing the through hole 25 on the glass substrate 92, a region where the evaporation material 98 can easily reach and a region where it is difficult to reach occur. Therefore, it is necessary to save expensive deposition materials by increasing the efficiency of use of deposition materials (film formation efficiency: ratio of adhesion to the glass substrate 92), and to perform deposition using expensive deposition materials stably and without unevenness within a desired area. For this purpose, it is important to configure the deposition mask 20 so that the obliquely moving deposition material 98 reaches the glass substrate 92 as much as possible. That is, in the cross section of FIGS. 4 to 6 perpendicular to the sheet surface of the deposition mask 20, the connecting portion 41 serving as the portion having the minimum cross-sectional area of the through hole 25 and the first concave portion 30 It is advantageous to sufficiently increase the minimum angle θ1 (see FIG. 4 ) formed by a straight line L1 passing through another arbitrary position of the wall surface 31 with respect to the normal direction of the deposition mask 20 .

As one of the methods for increasing the angle θ1, the thickness of the deposition mask 20 is reduced, whereby the wall surface 31 of the first concave portion 30 or the wall surface 36 of the second concave portion 35 is reduced. ) is considered to be small. That is, it can be said that it is preferable to use the metal plate 21 having a thickness as small as possible within a range capable of securing the strength of the deposition mask 20 as the metal plate 21 for constituting the deposition mask 20. .

As another method for increasing the angle θ1, optimizing the outline of the first concave portion 30 is also conceivable. For example, according to the present embodiment, when the wall surfaces 31 of the two adjacent first concave portions 30 join, compared to a concave portion having a wall surface (outline) indicated by a dotted line that does not join another concave portion, This angle θ1 can be greatly increased (see Fig. 4). The reason for this is explained below.

The first concave portion 30 is formed by etching the first surface 21a of the metal plate 21, as described in detail later. The wall surface of the concave portion formed by etching generally has a curved surface that becomes convex in the erosion direction. Therefore, the wall surface 31 of the concave portion formed by etching rises in the area on the etching start side, and in the area on the opposite side to the etching start side, that is, on the deepest side of the concave portion, the metal plate 21 ) with a relatively large slope with respect to the normal direction. On the other hand, in the illustrated deposition mask 20, since the wall surfaces 31 of the two adjacent first concave portions 30 are joined on the etching start side, the wall surfaces 31 of the two first concave portions 30 The outer contour of the portion 43 where the distal end edge 32 of ) joins is not a towering shape, but a chamfered shape. For this reason, the wall surface 31 of the first concave portion 30 forming most of the through hole 25 can be effectively inclined with respect to the normal direction of the deposition mask. That is, the angle θ1 can be increased.

According to the deposition mask 20 according to the present embodiment, in the entire area of the effective region 22, the inclination angle θ1 formed by the wall surface 31 of the first concave portion 30 with respect to the normal direction of the deposition mask is effectively reduced. can increase Thereby, vapor deposition in a desired pattern can be stably performed with high precision while effectively improving the utilization efficiency of the evaporation material 98 .

(ingredient)

Hereinafter, a material (metal plate) for constituting the above-described deposition mask 20 will be described. In order to obtain the deposition mask 20 having a small thickness, it is necessary to increase the rolling ratio when manufacturing a metal plate by rolling a base material. However, the larger the rolling ratio, the larger the stress remaining inside the metal sheet, that is, the residual stress. As a method of removing such residual stress, a method of heating a metal plate is known. However, when the residual stress is removed by heating, the external dimensions of the metal plate may change. For example, the dimension in the longitudinal direction of a metal plate may become short after heating a metal plate. This is because the residual stress inside the metal plate is removed to remove residual strain, or the arrangement of crystals to change to change the crystal density is induced. In the following description, a phenomenon in which the dimensions of the outer shape of the metal plate change due to heat is also referred to as "heat recovery".

Incidentally, the process of manufacturing the deposition mask 20 using the metal plate includes a process of applying heat to the metal plate. For example, in the step of forming a resist film on a metal plate, first, a coating solution containing a negative photosensitive resist material is applied onto the metal plate, and then the coating solution is dried by heat. At this time, since heat is applied to the metal plate, residual strain may be removed. Also in the step of developing the resist film, the resist film may be heated in order to increase the hardness of the resist film. Even at this time, since heat is applied to the metal plate, residual strain may be removed. Therefore, in the manufacturing process of the deposition mask, the aforementioned thermal recovery of the metal plate may occur. Also in the deposition process using the deposition mask 20, it is conceivable that predetermined heat is applied to the deposition mask 20, thereby generating heat recovery.

In addition, when the removal of residual strain due to heat occurs uniformly regardless of the position on the metal plate 21, the thermal recovery of the metal plate 21 also occurs uniformly regardless of the position on the metal plate 21. . That is, the rate of change (shrinkage rate) of the distance between two arbitrary points on the metal plate 21 becomes the same value as the position of the gauge point. On the other hand, when the removal of residual strain due to heat non-uniformly occurs depending on the position on the metal plate 21, the thermal recovery of the metal plate 21 also occurs non-uniformly depending on the position on the metal plate 21. That is, the rate of change (shrinkage rate) of the distance between two arbitrary points on the metal plate 21 becomes a different value depending on the position of the gauge point. In the following description, thermal restoration that occurs uniformly regardless of location is referred to as "uniform thermal restoration", and thermal restoration that occurs unevenly depending on location is referred to as "non-uniform thermal restoration".

Hereinafter, problems that may occur due to "non-uniform heat recovery" of the metal plate will be considered.

In the deposition process when the deposition mask 20 is used, as shown in FIG. 1 , a plurality of deposition masks 20 are installed on the frame 15 . Each deposition mask 20 is held by the frame 15 in an attached state. Therefore, when the thermal restoration of the metal plate 21 in the longitudinal direction occurs evenly without depending on the position in the width direction, by adjusting the amount of tension, the deposition on the frame 15 when installed The length of the mask 20 can be adjusted. That is, the position of the through hole 25 of the deposition mask 20 relative to the frame 15 can be ideally adjusted.

On the other hand, when the thermal recovery of the metal plate 21 in the longitudinal direction is non-uniform in the width direction, even if the plurality of deposition masks 20 are uniformly pulled, the through-holes in the respective deposition masks 20 The position of (25) cannot be ideally adjusted. In addition, the difference in the degree of heat recovery of the metal plate 21 in each deposition mask 20 is small enough to be impossible to visually confirm. Therefore, it is difficult to ideally adjust the position of the through hole 25 of each deposition mask 20 relative to the frame 15 by individually adjusting the amount of tension in each deposition mask 20 . For this reason, when thermal restoration of the metal plate 21 in the longitudinal direction occurs nonuniformly in the width direction, the position of the light emitting layer of the organic EL display device fabricated by the deposition process using the deposition mask 20 is the deposition mask It varies depending on the degree of variation in thermal recovery that occurred in (20). This causes variation in quality of the organic EL display device.

Under such a background, it becomes important to select and use a metal plate with a small variation in the amount of thermal recovery in the width direction. As described above, heat recovery in the manufacturing process of the deposition mask 20 occurs due to residual strain inside the metal plate used. Therefore, the use of a metal plate having a small variance in the amount of thermal recovery in the width direction corresponds to the use of a metal plate having a small variance in the amount of residual strain in the width direction.

Next, the present embodiment including these configurations and its actions and effects will be described. Here, first, a method for manufacturing a metal plate used for manufacturing a deposition mask will be described. Next, a method for manufacturing a deposition mask using the obtained metal plate will be described. After that, a method of depositing an evaporation material on a substrate using the obtained evaporation mask will be described.

(Method of manufacturing metal plate)

First, referring to FIGS. 7 (a), (b), 8 (a), (b), (c), 9a and 9b (a), (b), the method for manufacturing a metal plate explain about. Fig. 7(a) is a diagram showing a step of rolling a base material to obtain a metal plate having a desired thickness, and Fig. 7(b) is a diagram showing a step of annealing the metal plate obtained by rolling.

[rolling process]

First, as shown in Fig. 7 (a), a base material 55 composed of an invar material is prepared, and the base material 55 is rolled by a rolling device 56 including a pair of rolling rolls 56a and 56b. is conveyed along the conveyance direction indicated by the arrow D1. The base material 55 reached between the pair of rolling rolls 56a and 56b is rolled by the pair of rolling rolls 56a and 56b, and as a result, the base material 55 is reduced in thickness. , stretches along the conveying direction. Thereby, the long metal plate 64 of thickness t ₀ can be obtained. As shown in Fig. 7(a), the winding body 62 may be formed by winding the elongated metal plate 64 around the core 61. The specific value of the thickness t ₀ is not particularly limited, but is, for example, 0.020 mm or more and 0.100 mm or less.

7(a) merely shows an outline of the rolling process, and specific configurations and procedures for implementing the rolling process are not particularly limited. For example, the rolling process includes a hot rolling process in which the base material is processed at a temperature equal to or higher than the temperature at which the crystal arrangement of the invar material constituting the base material 55 is changed, or a base material is processed at a temperature equal to or lower than the temperature at which the crystal arrangement of the invar material is changed. A cold rolling process may be included.

[Slit process]

Then, you may perform the slit process of cutting out the both ends in the width direction of the elongate metal plate 64 obtained by the rolling process over the range of 3 mm or more and 5 mm or less, respectively. This slit process is performed to remove cracks that may occur at both ends of the long metal plate 64 due to rolling. By carrying out such a slit process, it is possible to prevent a phenomenon in which the elongated metal plate 64 is broken, that is, a so-called plate crack from occurring starting from a crack.

[Annealing Step]

After that, in order to remove the residual stress accumulated in the long metal plate 64 by rolling, the long metal plate 64 is annealed using an annealing device 57 as shown in FIG. 7(b). The annealing step may be performed while pulling the elongated metal plate 64 in the transport direction (longitudinal direction), as shown in Fig. 7(b). That is, the annealing process may be performed not as so-called batch annealing, but as continuous annealing while conveying. The period during which the annealing process is performed is appropriately set depending on the thickness of the elongated metal plate 64, the rolling ratio, and the like, but the annealing process is performed at 500°C for 60 seconds, for example. In addition, the said "60 seconds" means that the time required for the long metal plate 64 to pass through the space heated to 500 degreeC in the annealing apparatus 57 is 60 seconds.

By carrying out the annealing step, a long metal plate 64 having a thickness t ₀ in which residual strain is removed to some extent can be obtained. Also, the thickness t ₀ is usually equal to the maximum thickness Tb in the peripheral region 23 of the deposition mask 20 .

Moreover, you may manufacture the elongate metal plate 64 of thickness _t0 by repeating the above-mentioned rolling process, slit process, and annealing process multiple times. In (b) of FIG. 7 , an example in which the annealing step is performed while pulling the elongated metal plate 64 in the longitudinal direction is shown, but is not limited thereto, and the annealing step is performed by the elongated metal plate 64 as a core. It may be carried out in a state wound around (61). That is, batch type annealing may be performed. In addition, when the annealing step is performed in a state where the long metal plate 64 is wound around the core 61, the long metal plate 64 may have a tendency to bend depending on the winding diameter of the winding body 62. . Therefore, depending on the winding diameter of the winding body 62 or the material constituting the base material 55, it is advantageous to perform the annealing step while pulling the long metal plate 64 in the longitudinal direction.

In addition, the continuous annealing described above has the advantage of increasing the throughput of the process compared to the batch annealing, but has the disadvantage that the degree of residual strain removal becomes insufficient compared to the batch annealing. That is, it is considered that the above-described heat recovery is more likely to occur when continuous annealing is performed than when batch type annealing is performed.

[Cutting process]

After that, a cutting step is performed in which both ends of the elongated metal plate 64 in the width direction are cut out over a predetermined range, thereby adjusting the width of the elongated metal plate 64 to a desired width. In this way, the elongated metal plate 64 having desired thickness and width can be obtained.

[Inspection process]

Thereafter, an inspection step of inspecting the degree of heat recovery before and after subjecting the sample taken out of the obtained elongated metal plate 64 to heat treatment is performed. Fig. 8(a) is a plan view showing the elongated metal plate 64 obtained. In Fig. 8(a), the front end of the elongated metal plate 64 in the longitudinal direction is indicated by reference numeral 64c, and the rear end is indicated by reference numeral 64d. In the inspection step, first, the sample metal plate 75 having a predetermined length in the longitudinal direction is obtained by cutting the elongated metal plate 64 along the width direction of the elongated metal plate 64 . At least one sample metal plate 75 is cut out from the elongated metal plate 64 constituting one winding body 62 . For example, as indicated by a dotted line in FIG. 8(a), the sample metal plate 75 is cut in two at the front end 64c of the long metal plate 64, and the rear end of the long metal plate 64. In (64d), two are cut out. In Fig. 8(b), four sample metal plates 75 cut from one long metal plate 64 are shown.

Next, a plurality of samples 76 are obtained by cutting the sample metal plate 75 into a plurality of pieces along the longitudinal direction of the metal plate. For example, as indicated by dotted lines in Fig. 8(b), the sample metal plate 75 is divided into 10 equal parts in the width direction. Fig. 8(c) shows a total of 40 samples 76 cut out from the four sample metal plates 75.

After that, the distance between the two measurement points 76a on each sample 76 is measured under a temperature condition of 25° C. before and after subjecting each sample 76 to heat treatment. As shown in FIG. 9A, the heat treatment includes a first step S1 in which the temperature of each sample 76 is raised from P1 to P2 over time Z1, and the temperature of each sample 76 is reduced to temperature P1 over time Z2. 2nd process S2 which maintains, and 3rd process S3 which makes the temperature of each sample 76 decrease from P2 to P1 over time Z3 are included. The times Z1 , Z2 , and Z3 and the temperatures P1 and P2 are set so that heat applied to the metal plate 21 can be simulated in the manufacturing process of the deposition mask 20 . For example, Z1, Z2, and Z3 are set to 30 minutes, 5 minutes, and 60 minutes, respectively, and temperatures P1 and P2 are set to room temperature (eg, 25°C) and 300°C, respectively.

In the first step, as shown in FIG. 9A , the sample 76 is heated so that the temperature rises from the temperature P1 (25° C.) to the temperature P2 (300° C.) at a uniform rate (heating rate). Similarly, in the third step, the sample 76 is cooled so that the temperature decreases at a uniform rate (temperature cooling rate) from the temperature P2 (300°C) to the temperature P1 (25°C).

Fig. 9B (a) is a plan view showing the sample 76 before heat treatment, and Fig. 9B (b) is a plan view showing the sample 76 after heat treatment. 9B (a) and (b), two measurement points in the longitudinal direction of the sample 76 before and after the heat treatment is applied to the sample 76, that is, in the longitudinal direction of the elongated metal plate 64. The distance between 76a is indicated by reference numerals L1 and L2, respectively. The two measurement points 76a are, for example, a distance L1 before heat treatment is applied to the sample 76, an appropriate distance for evaluating the degree of thermal recovery of each sample 76, for example, about It is set so that it may become 500 mm. In (a) and (b) of FIG. 9B , for convenience of description, the difference between the distances L1 and L2 is expressed larger than the actual one.

In (a) and (b) of FIG. 9B , two measurement points 76a are set so as to be arranged along the longitudinal direction of the sample 76 . However, the method of arranging the measurement points 76a is not particularly limited as long as it is possible to appropriately observe the thermal recovery of the sample 76.

The method of imprinting the two measuring points 76a on the sample 76 is not particularly limited, but, for example, the measuring points 76a are marked on the sample 76 as marks such as scars formed on the sample 76. .

After measuring the distances L1 and L2 between the two measuring points 76a in the longitudinal direction of the sample 76 before and after the heat treatment, based on the following formula, the thermal recovery rate F of the sample 76 yields

F={(L1-L2)/L1}×10 ⁶ (unit: ppm)

In this way, the thermal recovery rate F is defined as a percentage of the difference between the distances L1 and L2 before and after the heat treatment relative to the distance L1 between the two measurement points 76a in the sample 76 before the heat treatment. For example, when L1 is 500 mm and L2 is 499.995 mm, the heat recovery factor F is +10 ppm. All measurements of the distances L1 and L2 are performed under the condition of the temperature P1, that is, at normal temperature (25°C).

By the way, the above-mentioned elongated metal plate 64 may have a wavy shape due to the fact that the elongation rate of the elongated metal plate 64 at the time of the rolling step differs depending on the position in the width direction. When such a wavy shape appears, the distances L1 and L2 described above may be distances obtained by scanning the surface of the sample 76 along the wavy shape in consideration of the wavy shape, or may be distances ignoring the wavy shape. In either measurement method, the degree of thermal recovery occurring in the sample 76 can be evaluated.

For example, in the examples described later, the results of measuring the distances L1 and L2 of the sample 76 using an automatic two-dimensional coordinate measuring machine AMIC-710 manufactured by Shinto S Precision Co., Ltd. In this case, The distances L1 and L2 are distances on XY coordinates ignoring the wavy shape of the sample 76. The AMIC-710 also includes a function of making the environmental temperature of the measurement target, that is, the environmental temperature of the sample 76 constant. For this reason, by using the AMIC-710, stable measurement unaffected by temperature changes becomes possible.

After that, based on the obtained value of the thermal recovery factor F, the elongated metal plate 64 is sorted. Here, the elongated metal plate 64 is selected so that only the elongated metal plate 64 that satisfies all of the following conditions (1) and (2) is used in the manufacturing process of the deposition mask 20 described later.

(1) The average value K1 of the heat recovery rate F in each sample 76 is -10 ppm or more and +10 ppm or less.

(2) Variation K2 in thermal recovery rate F in each sample 76 is 20 ppm or less.

The variation K2 of the thermal recovery rate F in each sample 76 is obtained by multiplying the standard deviation σ ₁ of the thermal recovery rate F in a predetermined number of samples 76, for example, 40 samples 76 by 3. value that is calculated. That is, 3σ ₁ is employed as the deviation K2.

The above condition (1) means that the average value K1 of the thermal recovery rate F in each sample 76 is sufficiently smaller than the positional accuracy required for the through hole 25 of the deposition mask 20. Therefore, by using the long metal plate 64 for which condition (1) is satisfied, the dimension of the metal plate 21 constituting the deposition mask 20 is reduced due to the heat recovery during the manufacturing process of the deposition mask 20. It is possible to prevent the mask 20 from being changed to an extent that affects the quality. For this reason, the work of adjusting the position of the through hole 25 formed in the metal plate 21 for each lot in consideration of the thermal recovery rate, and the amount of tension when installing the plurality of deposition masks 20 on the frame 15 are reduced. , the work of adjusting for each lot in consideration of the heat recovery rate becomes unnecessary.

The above condition (2) means that the variation K2 of the thermal recovery rate F in each sample 76 is sufficiently small compared to the degree of positional accuracy required for the through hole 25 of the deposition mask 20. . Therefore, by using the elongated metal plate 64 satisfying the condition (2), the deviation of the positions of the through holes 25 in the plurality of deposition masks 20 obtained from one elongated metal plate 64 is within the permissible range. can be made within For this reason, it is possible to suppress variation in the position of the deposition material deposited on the substrate by the individual in the deposition process using the plurality of deposition masks 20 installed on the frame 15 . Therefore, in the case of forming the pixels of the organic EL display device by deposition, the pixel positioning accuracy of the organic EL display device can be improved. This makes it possible to take out the light emitted from each pixel without waste. That is, the luminous efficiency of each pixel can be increased.

(Manufacturing method of vapor deposition mask)

Next, a method of manufacturing the deposition mask 20 using the long metal plate 64 selected as described above will be described mainly with reference to FIGS. 10 to 19 . In the manufacturing method of the deposition mask 20 described below, as shown in FIG. 10, an elongated metal plate 64 is supplied, a through hole 25 is formed in the elongated metal plate 64, and a further elongated metal plate By cutting (64), the deposition mask 20 including the sheet metal plate 21 is obtained.

More specifically, a method of manufacturing the deposition mask 20, a step of supplying a long metal plate 64 extending in a band shape, and etching using a photolithography technique to the long metal plate 64 to form a long metal plate 64. Then, the elongated metal plate 64 is subjected to a step of forming the first concave portion 30 from the first surface 64a side and etching using a photolithography technique to form a second surface 64b on the elongated metal plate 64. It includes the process of forming the 2nd concave part 35 from the side. And the through hole 25 is produced in the long metal plate 64 by the 1st recessed part 30 and the 2nd recessed part 35 formed in the long metal plate 64 communicating with each other. In the example shown in FIG. 11, the formation process of the 2nd concave part 35 is performed before the formation process of the 1st concave part 30, and also the formation process of the 2nd concave part 35 and the 1st concave part Between the formation process of the part 30, the process of sealing the produced 2nd recessed part 35 is further provided. Below, the detail of each process is demonstrated.

10 shows a manufacturing apparatus 60 for manufacturing the deposition mask 20 . As shown in FIG. 10, first, a winding body 62 in which a long metal plate 64 is wound around a core 61 is prepared. Then, as this core 61 rotates and the winding body 62 is unwound, a long metal plate 64 extending in a belt shape as shown in FIG. 10 is supplied. In addition, the long metal plate 64 is formed with a through hole 25 to form a sheet-shaped metal plate 21 and further a deposition mask 20 .

The supplied long metal plate 64 is conveyed to an etching device (etching means) 70 by a conveyance roller 72 . By the etching means 70, each process shown in Figs. 11 to 19 is performed. In this embodiment, it is assumed that a plurality of deposition masks 20 are allocated in the width direction of the elongated metal plate 64 . That is, a plurality of deposition masks 20 are fabricated from regions occupying predetermined positions of the elongated metal plate 64 in the longitudinal direction. In this case, if the thermal recovery rate of the elongated metal plate 64 fluctuates in the width direction, the length of the obtained deposition mask 20 and the total pitch described later also fluctuate.

First, as shown in FIG. 11, on the first surface 64a of the elongated metal plate 64 (on the lower surface in the paper of FIG. 11) and on the second surface 64b, a negative shape is formed. A coating liquid containing a photosensitive resist material is applied to form resist films 65c and 65d.

Next, exposure masks 85a and 85b are prepared so as not to transmit light to a region to be removed among the resist films 65c and 65d, and the exposure masks 85a and 85b are applied with a resist as shown in FIG. 12, respectively. It is placed on the films 65c and 65d. As the exposure masks 85a and 85b, for example, a dry glass plate is used so that light is not transmitted to a region to be removed in the resist films 65c and 65d. Thereafter, the exposure masks 85a and 85b are sufficiently brought into close contact with the resist films 65c and 65d by vacuum adhesion.

Further, as the photosensitive resist material, a positive-type one may be used. In this case, as an exposure mask, an exposure mask that transmits light to a region to be removed in the resist film is used.

After that, the resist films 65c and 65d are exposed over the exposure masks 85a and 85b. Additionally, the resist films 65c and 65d are developed to form images on the exposed resist films 65c and 65d (development process). As described above, as shown in FIG. 13, a resist pattern (simply referred to as a resist) 65a is formed on the first surface 64a of the elongated metal plate 64, and the second surface of the elongated metal plate 64 is formed. A resist pattern (simply referred to as a resist) 65b may be formed on the second surface 64b. Further, the developing step may include a resist heat treatment step for increasing the hardness of the resist films 65c and 65d. In the resist heat treatment step, heat treatment is performed for 5 minutes under a temperature condition of, for example, 300°C.

Next, as shown in FIG. 14, using the resist pattern 65b formed on the elongated metal plate 64 as a mask and using an etchant (for example, ferric chloride solution), the elongated metal plate 64 is coated with a second layer. Etching is performed from the surface 64b side. For example, the second surface 64b of the elongated metal plate 64 is passed over the resist pattern 65b from a nozzle disposed on the side facing the second surface 64b of the elongated metal plate 64 to which the etchant is conveyed. sprayed towards As a result, as shown in Fig. 14, erosion by the etchant proceeds in the region of the elongated metal plate 64 not covered by the resist pattern 65b. As described above, a large number of second concave portions 35 are formed in the elongated metal plate 64 from the second surface 64b side.

After that, as shown in Fig. 15, the formed second concave portion 35 is coated with a resin 69 resistant to the etching solution. That is, the second concave portion 35 is sealed by the resin 69 having resistance to the etching solution. In the example shown in Fig. 15, a film of resin 69 is formed so as to cover not only the formed second concave portion 35 but also the second surface 64b (resist pattern 65b).

Next, as shown in Fig. 16, the elongated metal plate 64 is etched for the second time. In the etching of the second time, the long metal plate 64 is etched only from the first surface 64a side, and formation of the first concave portion 30 proceeds from the first surface 64a side. This is because the second surface 64b side of the elongated metal plate 64 is coated with a resin 69 resistant to an etching solution. Therefore, the shape of the second concave portion 35 formed into a desired shape by the first etching is not damaged.

Erosion by etching is performed in a part of the elongated metal plate 64 that is in contact with the etchant. Therefore, erosion does not proceed only in the normal direction (thickness direction) of the elongated metal plate 64, but also proceeds in a direction along the plate surface of the elongated metal plate 64. As a result, as shown in FIG. 17, etching proceeds in the normal direction of the elongated metal plate 64 so that the first concave portion 30 not only contacts the second concave portion 35, but also the resist pattern 65a. The two first concave portions 30 respectively formed at positions facing the adjacent two holes 66a merge on the other side of the bridge portion 67a located between the two holes 66a.

As shown in Fig. 18, etching from the side of the first surface 64a of the long metal plate 64 proceeds further. As shown in FIG. 18, a merging portion 43 formed by merging two adjacent first concave portions 30 is spaced apart from the resist pattern 65a, and the merging portion 43 below the resist pattern 65a ), erosion by etching also proceeds in the normal direction (thickness direction) of the metal plate 64. As a result, the merging portion 43 sharp toward one side along the normal direction of the deposition mask is etched from one side along the normal direction of the deposition mask, and chamfered as shown in FIG. 18 . Accordingly, the inclination angle θ1 of the wall surface 31 of the first concave portion 30 with respect to the normal direction of the deposition mask can be increased.

In this way, the erosion of the first surface 64a of the elongated metal plate 64 by etching proceeds in the entire area constituting the effective area 22 of the elongated metal plate 64 . As a result, the maximum thickness Ta along the normal direction of the elongated metal plate 64 in the region constituting the effective region 22 becomes smaller than the maximum thickness Tb of the elongated metal plate 64 before etching.

As described above, the etching from the side of the first surface 64a of the elongated metal plate 64 proceeds by a predetermined amount, and the second etching of the elongated metal plate 64 is completed. At this time, the first concave portion 30 extends along the thickness direction of the long metal plate 64 to a position reaching the second concave portion 35, whereby the first concave portion 30 communicating with each other and a through hole 25 is formed in the long metal plate 64 by the second concave portion 35 .

Then, as shown in Fig. 19, the resin 69 is removed from the long metal plate 64. The film of the resin 69 can be removed, for example, by using an alkaline stripper. When an alkaline stripping solution is used, as shown in Fig. 19, the resist patterns 65a and 65b are removed simultaneously with the resin 69. After removing the resin 69, the resist patterns 65a and 65b may be removed separately from the resin 69.

The elongated metal plate 64 in which the plurality of through holes 25 are formed in this way is cut by a cutting device (cutting means) ( 73) is returned. Further, the supply core 61 described above is rotated through the tension (tensile stress) acting on the elongated metal plate 64 by the rotation of the conveying rollers 72 and 72, and the elongated metal plate ( 64) is to be supplied.

Thereafter, the long metal plate 64 on which a plurality of concave portions 30 and 35 are formed is cut into a predetermined length and width by a cutting device (cutting means) 73, so that a plurality of through holes 25 are formed in the sheet. A molded metal plate 21 is obtained.

As described above, the deposition mask 20 including the metal plate 21 in which many through holes 25 are formed is obtained. Here, according to the present embodiment, the first surface 21a of the metal plate 21 is etched over the entire area of the effective area 22 . For this reason, the thickness of the effective region 22 of the deposition mask 20 is reduced, and the front edge 32 of the wall surface 31 of the two first concave portions 30 formed on the first surface 21a side. The outer contour of the portion 43 where ) joins can be made into a chamfered shape. Therefore, the above-described angle θ1 can be increased, and thereby the efficiency of using the evaporation material and the positioning accuracy of the evaporation can be improved.

Moreover, according to this embodiment, the elongated metal plate 64 in which the average value and fluctuation|variation of the thermal recovery rate measured at each position in the width direction D2 was suppressed by conditions (1) and (2) mentioned above is used. For this reason, it is possible to suppress variations in the positions of the through holes 25 of the plurality of deposition masks 20 obtained from the elongated metal plate 64 for each individual.

(deposition method)

Next, a method of depositing an evaporation material on the substrate 92 using the obtained evaporation mask 20 will be described. As shown in FIG. 2, the deposition mask 20 is brought into close contact with the substrate 92 at first. At this time, as shown in FIG. 1 , a plurality of deposition masks 20 are mounted on the frame 15 so that the surface of the deposition mask 20 is parallel to the surface of the substrate 92 . Here, according to the present embodiment, the elongated metal plate 64 selected in advance based on the average value and variation of the thermal recovery rate in the width direction of the elongated metal plate 64 is used. For this reason, compared to the case where such sorting is not performed, the difference in length of the deposition mask 20 from the designed value and the variation in the length of the plurality of deposition masks 20 are suppressed. Therefore, deviation of the position of the through hole 25 of each deposition mask 20 relative to the frame 15 from the design value can be reduced. For this reason, the evaporation material can be deposited on the substrate 92 with high positional accuracy. Therefore, in the case of forming the pixels of the organic EL display device by deposition, the pixel positioning accuracy of the organic EL display device can be improved. This makes it possible to take out the light emitted from each pixel without waste. That is, the luminous efficiency of each pixel can be increased.

In this embodiment, an example in which the first surface 21a of the metal plate 21 is etched over the entire area of the effective area 22 is shown. However, it is not limited to this, and the first surface 21a of the metal plate 21 may be etched only in a part of the effective region 22 .

Further, in this embodiment, an example in which a plurality of deposition masks 20 are allocated in the width direction of the elongated metal plate 64 has been shown. In addition, in the deposition process, an example in which a plurality of deposition masks 20 are installed on the frame 15 has been shown. However, it is not limited thereto, and as shown in FIG. 20, the deposition mask 20 having a plurality of effective regions 22 arranged in a lattice shape along both the width direction and the length direction of the metal plate 21 may be used. Also in this case, by using the elongated metal plate 64 in which the variation in thermal recovery rate in the width direction is reduced, the degree of dimensional change caused by heat is suppressed from fluctuating depending on the position of the deposition mask 20 in the width direction. can In this way, in the deposition process, the positional accuracy of the deposition material deposited on the substrate can be increased.

Example

Next, the present invention will be described more specifically by examples, but the present invention is not limited to the description of the following examples unless the gist thereof is exceeded.

(First winding body and first sample)

First, a winding body (first winding body) in which a long metal plate is wound was manufactured by performing the above-described rolling process, slit process, annealing process, and cutting process with respect to a base material composed of an invar material.

Specifically, first, the first rolling step of performing the first hot rolling step and the first cold rolling step in this order is performed, and then, both ends of the elongated metal sheet in the width direction are each 3 mm or more 5 The 1st slit process of cutting out over the range of mm or less was implemented, and the 1st annealing process of continuously annealing a long metal plate was implemented after that at 500 degreeC over 60 second. Further, the second rolling step including the second cold rolling step is performed on the elongated metal plate that has passed through the first annealing step, and then both ends of the elongated metal plate in the width direction are 3 mm or more and 5 mm or less, respectively. The 2nd slit process of cutting out over a range was implemented, and the 2nd annealing process of continuously annealing a long metal plate over 60 second at 500 degreeC was implemented after that. In this way, a long metal plate 64 having a desired thickness and a width of about 600 mm was obtained. After that, both ends of the elongated metal plate 64 in the width direction are cut out over a predetermined range, thereby finally adjusting the width of the elongated metal plate 64 to a desired width, specifically, to a width of 500 mm. A cutting process was performed.

In addition, in the cold rolling process mentioned above, pressure adjustment using the backup roller was performed. Specifically, the shape and pressure of the back-up roller of the rolling mill were adjusted so that the shape of the elongated metal plate 64 became symmetrical. In addition, the cold rolling process was performed while cooling using rolling oil, for example, kerosene. After the cold rolling step, a washing step of washing the elongated metal plate with a hydrocarbon-based detergent was performed. After the washing step, the above-described slitting step was performed.

After that, the elongated metal plate 64 was cut along the width direction using shears to obtain a first sample metal plate including a metal plate with a width of 500 mm and a projected length of 700 mm. Here, two first sample metal plates were cut out at the front end of the elongated metal plate 64, and further, two first sample metal plates were cut out at the rear end of the elongated metal plate 64. In addition, the "projected length" is the metal sheet length (dimension in the rolling direction) when the metal sheet is viewed from directly above, that is, when the wavy shape of the metal sheet is ignored. The width of the first sample metal plate is the distance between a pair of end portions of the first sample metal plate in the width direction. The pair of end portions of the first sample metal plate are portions formed by passing through a cutting step of cutting both ends in the width direction of a metal plate obtained through the rolling step and the annealing step over a predetermined range, and extend substantially straight.

Next, each of the four first sample metal plates was divided into 10 equal parts along the longitudinal direction. Thus, a total of 40 first samples having a width of 50 mm and a projected length of 700 mm were obtained. Thereafter, two measurement points were imprinted on each first sample by scratching each first sample vigorously with a needle. The two measurement points were engraved so that an interval of about 500 mm was formed between the two measurement points in the longitudinal direction.

Next, heat treatment was performed on each of the first samples. In addition, the distances L1 and L2 between the two measuring points in the longitudinal direction of each first sample before and after the heat treatment were measured under a temperature condition of 25°C. In the heat treatment, first, the temperature of each first sample was raised from 25 ° C to 300 ° C over 30 minutes, then the temperature of each first sample was maintained at 300 ° C over 5 minutes, and then, The temperature of each first sample was decreased from 300°C to 25°C over 60 minutes. Here, as a measuring machine for performing heat treatment on each first sample and measuring the distance between two measuring points of each first sample, the above-described automatic two-dimensional coordinate measuring machine AMIC-710 manufactured by Shinto S Precision Co., Ltd. used Further, based on the measured distances L1 and L2, the heat recovery rate F described above was calculated.

As a result of the measurement, the average value K1 of the thermal recovery rate F in each of the first samples was -2 ppm, and the variation K2 in the thermal recovery rate was 16 ppm. When these measurement results were compared with conditions (1) and (2) described above, both conditions (1) and (2) were satisfied in the first sample. Therefore, it is determined that the first winding body from which the first sample is taken out can be used as a material for manufacturing a deposition mask.

[Evaluation of the primary effect]

Using the elongated metal plate of the first winding body from which the above-described first sample was obtained, a large number of deposition masks having five effective regions formed along the longitudinal direction were manufactured. A large number of through holes are formed in a regular arrangement in each effective region of each deposition mask. Next, in order to evaluate the positional accuracy of the obtained deposition mask, the total pitch of each deposition mask was measured, and the average value and deviation of the total pitch were calculated.

Here, the total pitch is the distance between two predetermined points in the deposition mask. As long as it is possible to evaluate the positional accuracy of the deposition mask, the two points are not particularly limited. Here, a predetermined mark formed in the vicinity of the effective area located on one end side of the deposition mask and the other of the deposition mask. The distance between predetermined marks formed in the vicinity of the effective area located on the end side was measured as a total pitch. The total pitch in this case is about 600 mm by design.

As an index of the degree of variation in total pitch, a value obtained by multiplying the standard deviation (σ ₂ ) of measured values of the total pitch of each deposition mask by 3, ie, 3σ ₂ , was used as in the case of the thermal recovery rate.

The average value of the measured values of the total pitch of the deposition mask obtained from the first winding body was 600.0018 mm, and the variation (3σ ₂ ) was 9.3 μm. In addition, the number of n at the time of calculating the standard deviation (σ ₂ ) provides sufficient certainty in performing a comparison between _deposition masks obtained from the second winding body to the tenth winding body described later. ) was set to have a value of Specifically, n number was set to 80 by measuring the total pitch at two places in each of the 40 first samples. In addition, the allowable range of the average value and deviation of the measured value of the total pitch of the deposition mask is determined according to the pixel density of the organic EL display device fabricated by using the deposition mask. For example, in the case of manufacturing an organic EL display device with a pixel density of 400 ppi, the average value of the measured values of the total pitch of the deposition mask is within the range of ±0.005 mm of the design value (eg 600.0000 mm), and the deposition mask It is required that the deviation of the measured value of the total pitch of 0.01 mm or less. By setting in this way, the total pitch of the obtained deposition mask can be placed within the range of the designed value (for example, 600.0000 mm) ± 0.015 mm, that is, within the range of the allowable value.

In addition, the total pitch of the deposition mask obtained from the first winding body was evaluated from the viewpoint of the process capability index. A process capability index is a numerical value of the quality achievement capability (process capability) of a process. In general, if the process capability index is 1.33 or higher, the quality achievement capability of the process can be said to be good.

Hereinafter, a method for calculating a process capability index will be described. The process capability index Cp in the case where the average value of the characteristic values of those manufactured as a result of the process can be adjusted is calculated by the following formula.

Cp=(USL-LSL)/(6×σ ₂ )

Here, USL and LSL are the upper standard value and the lower standard value, respectively. For example, in this embodiment, as described above, since the allowable value of the total pitch is 600.0000 mm±0.015 mm, the USL is 600.015 mm and the LSL is 599.985 mm. Further, "the average value of the characteristic values can be adjusted" means a case where the average value of the characteristic values can be made intermediate between USL and LSL by adjusting the process.

On the other hand, the process capability index Cpk when considering that the average value of the characteristic values deviate from the middle of USL and LSL is calculated by the following formula.

Cpk=(1-k)×Cp

Here, k is computed by the following formula.

Here, μ is an average value of measured values of the total pitch of the deposition mask obtained from the first winding body.

In this embodiment, the aforementioned Cpk is employed as the process capability index. The process capability index Cpk of the total pitch of the deposition mask obtained from the elongated metal plate of the first winding body was 1.42.

(Evaluation of the secondary effect)

An evaporation material was deposited on the substrate using an evaporation mask made of a long metal plate of the first winding body. In addition, the pattern of many through holes formed in the used deposition mask was a stripe pattern corresponding to a pixel density of 300 ppi. Further, as the deposition material, a green organic light emitting material emitting green light was used. Thereafter, the center coordinate positions of the plurality of green light emitting layers including the green organic light emitting material deposited on the substrate were measured. The measurement of the central coordinate position was performed for nine green light-emitting layers among a plurality of green light-emitting layers formed based on one effective area of the deposition mask. In the case of evaluating 10 deposition masks taken out from one long metal plate in the same manner as in the case of evaluation of each sample described above, if the number of effective regions existing in one deposition mask is 5, the green light emitting layer to be measured The number becomes 10 × 5 × 9 = 450.

For each of the measured center coordinate positions, the amount of deviation from the design value was calculated. In addition, the standard deviation σ ₃ of the shift amount was calculated. Then, it was determined whether the deviation (3σ ₃ ) of the shift amount was equal to or less than the allowable value. At this time, the allowable value of the deviation of the deviation amount of the central coordinate position was 10 µm. As a result, the deviation of the deviation amount of the central coordinate position was 8.7 μm. That is, the positional accuracy of the evaporation material was good.

(2nd to 10th winding bodies and 2nd to 10th samples)

In the same manner as in the case of the first winding body, the second winding body to the tenth winding body were manufactured from the base material composed of the invar material. In addition, similarly to the case of the first winding body, for the second to tenth winding bodies, the measurement of the thermal recovery rate of the samples taken out from each winding body, and to the deposition mask made of the long metal plate of each winding body Evaluation of the above-mentioned primary effect and evaluation of the secondary effect were performed.

(Summary of judgment results of each sample)

The measurement result of the heat recovery rate of each sample taken out from the 1st winding body - the 10th winding body is shown in FIG. As shown in Fig. 21, in the first, second, third and fifth samples, the judgment result was "○". That is, both conditions (1) and (2) described above were satisfied. On the other hand, in the 4th, 6th, 7th, 8th, 9th, and 10th samples, the judgment result was "x". That is, at least one of the above conditions (1) or (2) was not satisfied. Specifically, in the seventh, eighth, and ninth samples, the above-described condition (1) was not satisfied. In addition, in the fourth and sixth samples, the above condition (2) was not satisfied. In Sample 10, both conditions (1) and (2) were not satisfied.

(Summary of evaluation results of primary effect and secondary effect)

The evaluation results of the above-described primary effect and secondary effect of the deposition mask made of the long metal plates of the first to tenth winding bodies are shown in FIGS. 22 and 23 , respectively.

As shown in Figs. 22 and 23, for the deposition mask produced using the elongated metal plates obtained from the first, second, third and fifth winding bodies, the determination result of the evaluation of the primary effect and the secondary effect The judgment results of evaluation were all "○". Specifically, for the first order effect, as shown in FIG. 22, the average value of the total pitch (TP) is within the range of 600.0000 mm ± 0.005 mm, the deviation of TP is 0.01 mm or less, and the process capability index Cpk was set to 1.33 or higher. Regarding the secondary effect, as shown in Fig. 23, the variation in the shift amount of the central coordinate position of the produced green light emitting layer was 10 µm or less.

On the other hand, in the deposition masks produced using the elongated metal plates obtained from the fourth, sixth, seventh, eighth, ninth, and tenth winding bodies, the determination result of the evaluation of the primary effect and the evaluation of the secondary effect The judgment results were all "x". Specifically, for the first-order effect, the process capability index Cpk was less than 1.33, and for the second-order effect, the deviation of the center coordinate position of the produced green light emitting layer exceeded 10 µm. Moreover, in the vapor deposition mask produced using the elongate metal plate obtained from the 6th - 10th winding bodies, the average value of TP was outside the range of 600.0000 mm +/-0.005 mm. Moreover, in the vapor deposition mask produced using the elongate metal plate obtained from the 10th winding body, the variance of TP exceeded 0.01 mm.

21, 22, and 23, the judgment results based on the conditions (1) and (2) described above and the judgment results based on the first-order effect and the second-order effect are completely consistent. there was. That is, by using the conditions (1) and (2) described above, the process capability index in the manufacturing process of the deposition mask can be increased, and the elongated metal plate 64 capable of forming the light emitting layer with high positional accuracy can be obtained. can be said to be selectable. That is, it is considered that conditions (1) and (2) described above are effective judgment methods for sorting the elongated metal plate 64.

20: deposition mask
21: metal plate
21a: first surface of metal plate
21b: second side of metal plate
22: effective area
23: surrounding area
25: through hole
30: first concave portion
31: wall
35: second recess
36: wall
55: parent material
56: rolling device
57: annealing device
61: core
62: winding body
64: long metal plate
64a: first side of long metal plate
64b: second side of long metal plate
65a, 65b: resist pattern
65c, 65d: resist film
85a, 85b: exposure mask

Claims (5)

It is a deposition mask,
A metal plate including a first surface and a second surface;
an effective area formed with a plurality of through holes penetrating the metal plate;
A peripheral area surrounding the effective area is provided;
the plurality of through holes are arranged at a predetermined pitch along two directions orthogonal to each other in the effective area;
The through hole includes a first concave portion located on a side of the first surface and a second concave portion located on a side of the second surface and connected to the first concave portion;
The deposition mask of claim 1 , wherein a maximum thickness of the metal plate in the effective region is smaller than a maximum thickness of the metal plate in the peripheral region. According to claim 1,
and a maximum thickness of the effective region in a cross section along the two directions is smaller than a maximum thickness of the effective region in a cross section in a direction different from the two directions. According to claim 2,
A deposition mask in which two adjacent first concave portions are connected in each of the two directions. According to claim 2 or 3,
wherein corners of the two through holes face each other in a direction different from the two directions. According to claim 4,
The deposition mask according to claim 1 , wherein two adjacent first concave portions are connected in directions different from the two directions.

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